Why the value of "Logical Reads" in AWR greater than the one from v$segment_statistics

Hi,

Why the value of "Logical Reads" in AWR greater than the one from v$segment_statistics?

For example, in our database:

The value of "Logical Reads" from AWR "Segments by Logical Reads" section, is 327,735,648 for 1 day.

The value of "Logical Reads" from v$segment_statistics, is 83,080,880 from instance startup (for more than 6 days)

SQL> select value,statistic_name from v$segment_statistics where STATISTIC_NAME='logical reads' and OBJECT_NAME='TOAPLOG';

      VALUE STATISTIC_NAME

----------- ------------------

 83,080,880 logical reads